Semiconductor device with shielding structure for cross-talk reduction

ABSTRACT

A method includes embedding a die in a molding material; forming a first dielectric layer over the molding material and the die; forming a conductive line over an upper surface of the first dielectric layer facing away from the die; and forming a second dielectric layer over the first dielectric layer and the conductive line. The method further includes forming a first trench opening extending through the first dielectric layer or the second dielectric layer, where a longitudinal axis of the first trench is parallel with a longitudinal axis of the conductive line, and where no electrically conductive feature is exposed at a bottom of the first trench opening; and filling the first trench opening with an electrically conductive material to form a first ground trench.

PRIORITY CLAIM AND CROSS-REFERENCE

This patent is a continuation of U.S. application Ser. No. 15/950,722,filed on Apr. 11, 2018, entitled “Semiconductor Device with ShieldingStructure for Cross-talk Reduction”, which claims priority to U.S.Provisional Application No. 62/527,907, filed Jun. 30, 2017, entitled“Integrated Fan-Out Package with Electromagnetic Shielding,” whichapplications are hereby incorporated by reference in their entireties.

BACKGROUND

As semiconductor technologies further advance, new packaging techniquesare used to accommodate the shrinking die size. For example, in anintegrated fan-out (InFO) package, a die is embedded in a moldingmaterial. Redistribution structures are formed over the molding materialand the die, which redistribution structures include conductive featuressuch as conductive lines and vias formed in one or more dielectriclayers. The conductive features of the redistribution structure areelectrically coupled to the die.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIGS. 1-9 and 10A-10D illustrate cross-sectional views of asemiconductor device at various stages of fabrication, in accordancewith an embodiment.

FIGS. 11A-11C illustrate cross-sectional views of a semiconductordevice, in accordance with an embodiment.

FIGS. 12A-12C illustrate cross-sectional views of a semiconductordevice, in accordance with an embodiment.

FIGS. 13A-13D illustrate cross-sectional views of a semiconductordevice, in accordance with an embodiment.

FIGS. 14A-14E illustrate cross-sectional views of a semiconductordevice, in accordance with an embodiment.

FIGS. 15A-15D illustrate cross-sectional views of a semiconductordevice, in accordance with an embodiment.

FIG. 15E and FIG. 15F each illustrates a cross-sectional view of asemiconductor device, in accordance with some embodiments.

FIGS. 16A-16D illustrate cross-sectional views of a semiconductordevice, in accordance with an embodiment.

FIGS. 17A-17D illustrate cross-sectional views of a semiconductordevice, in accordance with an embodiment.

FIG. 18 illustrates a flow chart of method of making a semiconductordevice, in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the invention. Specificexamples of components and arrangements are described below to simplifythe present disclosure. These are, of course, merely examples and arenot intended to be limiting. For example, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed between the first and second features, such thatthe first and second features may not be in direct contact.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Embodiments of the present disclosure are discussed in the context offorming a semiconductor device, and in particular, in the context offorming electrically grounded shielding structures in a semiconductorpackage for reducing or eliminating cross-talk between signal lines. Inaccordance with some embodiments, ground trenches are formed in aredistribution structure of a semiconductor package. The ground trenchesare disposed on opposing sides of a conductive line that carriesinformation bearing signals. In some embodiments, ground vias are formedon top of and are connected to the ground trenches. In some embodiments,a ground plane is formed over the conductive line, the ground trenches,and the ground vias (if formed), and are connected to the groundedtrenches and the ground vias (if formed). The ground trenches, groundvias (if formed), and the ground plane (if formed) form a groundedshielding structure (e.g., an electrically conductive structure that isgrounded) around the conductive line to reduce cross-talk between theconductive line and neighboring conductive lines.

FIGS. 1-9 and 10A-10D illustrate cross-sectional views of asemiconductor device 100 at various stages of fabrication, in accordancewith an embodiment. In FIG. 1, a semiconductor die 107 (may also bereferred to as a die, a chip, or an integrated circuit (IC) die) isattached to a carrier 101. The carrier 101 may be made of a materialsuch as silicon, polymer, polymer composite, metal foil, ceramic, glass,glass epoxy, beryllium oxide, tape, or other suitable material forstructural support. A dielectric layer 103, which may serve as a releaselayer, is deposited or laminated over the carrier 101, as illustrated inthe example of FIG. 1. The dielectric layer 103 may be photosensitiveand may be easily detached from the carrier 101 by shining, e.g., anultra-violet (UV) light on the carrier 101 in a subsequent carrierde-bonding process. For example, the dielectric layer 103 may be alight-to-heat-conversion (LTHC) coating made by 3M Company of St. Paul,Minn.

As illustrated in FIG. 1, the die 107 is attached to the dielectriclayer 103 via an adhesive layer 102, which may be a die attaching film(DAF), a glue layer, or other suitable material. Before being adhered tothe dielectric layer 103, the die 107 may be processed according toapplicable manufacturing processes to form integrated circuits in thedie 107. For example, the die 107 includes a semiconductor substrate106, such as silicon, doped or undoped, or an active layer of asemiconductor-on-insulator (SOI) substrate. The semiconductor substratemay include other semiconductor materials, such as germanium; a compoundsemiconductor including silicon carbide, gallium arsenic, galliumphosphide, gallium nitride, indium phosphide, indium arsenide, and/orindium antimonide; an alloy semiconductor including SiGe, GaAsP, AlInAs,AlGaAs, GaInAs, GaInP, and/or GaInAsP; or combinations thereof. Othersubstrates, such as multi-layered or gradient substrates, may also beused. Devices (not shown), such as transistors, diodes, capacitors,resistors, etc., may be formed in and/or on the semiconductor substrate106 and may be interconnected by interconnect structures (not shown)formed by, for example, metallization patterns in one or more dielectriclayers on the semiconductor substrate 106 to form an integrated circuit.

The die 107 further comprise pads (also referred to as contact pads, notshown), such as aluminum pads, to which external connections are made.The pads are on what may be referred to as an active side or a frontside of the die 107. Passivation films (not shown) are on the activeside of die 107 and on portions of the pads. Openings are formed throughthe passivation films to the pads. Die connectors 109, such asconductive pillars (e.g., comprising a metal such as copper), are in theopenings through passivation films and are mechanically and electricallycoupled to the respective pads. The die connectors 109 may be formed by,for example, plating, or the like. The die connectors 109 electricallycouple the integrated circuit of the die 107.

A dielectric material 108 is on the active sides of the die 107, such ason the passivation films and the die connectors 109. The dielectricmaterial 108 laterally encapsulates the die connectors 109, and thedielectric material 108 is laterally coterminous with the die 107. Thedielectric material 108 may be a polymer such as polybenzoxazole (PBO),polyimide, benzocyclobutene (BCB), or the like; a nitride such assilicon nitride or the like; an oxide such as silicon oxide;phosphosilicate glass (PSG), borosilicate glass (BSG), boron-dopedphosphosilicate glass (BPSG), or the like; or a combination thereof, andmay be formed, for example, by spin coating, lamination, CVD, or thelike.

Next, in FIG. 2, a molding material 105 is formed over the dielectriclayer 103 to encapsulate the die 107. The molding material 105 maycomprise an epoxy, an organic polymer, a polymer with or without asilica-based or glass filler added, or other materials, as examples. Insome embodiments, the molding material 105 comprises a liquid moldingcompound (LMC) that is a gel type liquid when applied. The moldingmaterial 105 may also comprise a liquid or solid when applied.Alternatively, the molding material 105 may comprise other insulatingand/or encapsulating materials. The molding material 105 is appliedusing a wafer level molding process in some embodiments. The moldingmaterial 105 may be molded using, for example, compressive molding,transfer molding, or other suitable methods.

Next, the molding material 105 is cured using a curing process, in someembodiments. The curing process may comprise heating the moldingmaterial 105 to a predetermined temperature for a predetermined periodof time, using an anneal process or other heating process. The curingprocess may also comprise an ultra-violet (UV) light exposure process,an infrared (IR) energy exposure process, combinations thereof, or acombination thereof with a heating process. Alternatively, the moldingmaterial 105 may be cured using other methods. In some embodiments, acuring process is not included.

After the molding material 105 is deposited and cured (if needed), aplanarization process, such as chemical mechanical polish (CMP), isperformed to remove a top portion of the molding material 105 and toexpose upper surfaces of the die connectors 109 of the die 107, in someembodiments.

Next, in FIG. 3, a dielectric layer 110 is formed over the moldingmaterial 105 and the die 107. The dielectric layer 110 is formed of apolymer, such as PBO, polyimide, BCB, or the like. In other embodiments,the dielectric layer 110 is formed of a nitride such as silicon nitride;an oxide such as silicon oxide; PSG, BSG, BPSG, or the like; or thelike. The dielectric layers 110 may be formed by any acceptabledeposition process, such as spin coating, chemical vapor deposition(CVD), laminating, the like, or a combination thereof. A planarizationprocess, such as CMP, may be performed to achieve a planar upper surfacefor the dielectric layer 110.

Next, the dielectric layer 110 is patterned using, e.g., lithographyand/or etching processes to form openings, such as via openings 111 andtrench openings 112. The via openings 111 expose the die connectors 109,in the example of FIG. 3. The trench opening 112 in FIG. 3 exposes themolding material 105, and no electrically conductive feature (e.g.,conductive lines, vias, or die connectors) is exposed by the bottom ofthe trench opening 112. A longitudinal axis 112L of the trench opening112 is parallel to an upper surface 150U of the molding material 105,which upper surface 105U is parallel to the upper surfaces of thedielectric layers (e.g., 110, 120, 130 and 140, see FIG. 9) disposedover the molding material 105, in some embodiments. The longitudinalaxis 112L of the trench opening 112 is parallel to a longitudinal axis113SL of a signal line 113S (see FIG. 10D) formed in subsequentprocessing, in some embodiments. The location of the trench opening 112as illustrated in FIG. 3 is merely a non-limiting example. The trenchopenings 112 may be formed over any other suitable region, such as over(e.g., directly over) the die 107. In embodiments where the trenchopening 112 is formed directly over the die 107, the trench opening 112is formed over areas of the die 107 that does not have conductivefeatures (e.g., die connectors 109 of FIG. 3, or line vias 104 of FIG.17A), thus no electrically conductive feature is exposed by the bottomof the trench opening 112. These and other variations are fully intendedto be included within the scope of the present disclosure.

Next, in FIG. 4, electrically conductive features, such as conductivelines 113, conductive vias 115, and ground trenches 117 are formed overand/or in the dielectric layer 110. The conductive features may beformed of a suitable conductive material such as copper, titanium,tungsten, aluminum, or the like. The conductive features may be formedby, e.g., forming a seed layer over the dielectric layer 110 and in theopenings 111/112, forming a patterned photoresist with a designedpattern over the seed layer, plating (e.g., electroplating orelectroless plating) the conductive material in the designed pattern andover the seed layer, and removing the photoresist and portions of seedlayer on which the conductive material is not formed. In otherembodiments, the conductive features are formed by a subtractiveprocess, e.g., by blanket deposition of the conductive material over theupper surface of the dielectric layer 110, followed by patterning and/oretching of the deposited conductive material.

Note that ground trenches 117 are formed by filling the trench openings112 (see FIG. 3) with an electrically conductive material. Since noelectrically conductive feature is exposed by the bottom of the trenchopening 112, no electrically conductive feature is connected to (e.g.,physically contacts) the bottom surface of the ground trench 117, insome embodiments. Therefore, the bottom surface of the ground trench 117physically contacts a dielectric material (e.g., the molding material105), in some embodiments. In contrast, the conductive via 115 is formedsuch that a bottom surface of the conductive via 115 is connected with(e.g., physically contacts) an underlying electrically conductivefeature. Compared with the conductive via 115, which may have alongitudinal axis perpendicular to the upper surface 105U of the moldingmaterial 105, the ground trench 117 has a longitudinal axis 117L (seealso FIG. 10D) parallel to the upper surface 105U of the moldingmaterial 105. In the illustrated example of FIG. 4, the ground trench117 is electrically coupled to other electrically conductive features(e.g., conductive lines 113A and 113B) through an upper surface of theground trench 117 or through an upper portion of the ground trench 117that is disposed over the upper surface of the dielectric layer 110, insome embodiments. More details of the ground trench are discussedhereinafter with reference to FIGS. 10A-10D.

Next, in FIG. 5, a dielectric layer 120 is formed over the dielectriclayer 110 and the conductive features (e.g., 113, 115, and 117) formedin FIG. 4. The dielectric layer 120 may comprise a same or a similarmaterial as the dielectric layer 110, and may be formed by a same orsimilar formation method as the dielectric layer 110, thus details arenot repeated. A planarization process, such as CMP, may be performed toachieve a planar upper surface for the dielectric layer 120.

Next, the dielectric layer 120 may be patterned, e.g., byphotolithography and/or etching processes, to form openings 121 and 122.Openings 121 expose underlying conductive features, such as conductivelines 113 and/or conductive vias 115, and openings 122 expose the groundtrench 117, in some embodiments.

Next, in FIG. 6, electrically conductive features, such as conductivelines 123/129 and conductive vias 125/128 are formed over and/or in thedielectric layer 120. The conductive features 123, 129, 125, and 128 maybe formed of a same or a similar material as the conductive features 113and 115, and may be formed using a same or similar method as theconductive features 113 and 115, thus details are not repeated.

The conductive vias 128 are electrically and mechanically coupled to theground trench 117, in the illustrated embodiment. The conductive vias128 may also be connected together by the conductive line 129 disposedover the upper surface of the dielectric layer 120, as illustrated inFIG. 6. The conductive vias 128 over a same ground trench 117 aredisposed along a line, which may overlap with or be parallel to (seeFIG. 10C) the longitudinal axis 117L of the ground trench 117, in someembodiments. As discussed in more details hereinafter, the conductivevias 128 are electrically grounded and form an electrically groundedshielding structure with the ground trenches 117 to reduce cross-talk,thus the conductive vias 128 are also referred to as ground vias 128 inthe discussion hereinafter. More details of the ground vias 128 arediscussed hereinafter with reference to FIGS. 10A-10D.

Next, in FIG. 7, a dielectric layer 130 is formed over the dielectriclayer 120 and the conductive features 123, 125, 128, and 129, and ispatterned to form openings 131, which openings 131 expose respectiveunderlying conductive features. The dielectric layer 130 may comprise asame or a similar material as the dielectric layer 110, and may beformed by a same or similar formation method as the dielectric layer110, thus details are not repeated. A planarization process, such asCMP, may be performed to achieve a planar upper surface for thedielectric layer 130.

Next, in FIG. 8, electrically conductive features, such as conductivelines 133 and conductive vias 135 are formed over and/or in thedielectric layer 130. The conductive features (e.g., 133, 135) may beformed of a same or a similar material as the conductive features 113and 115, and may be formed using a same or similar method as theconductive features 113 and 115, thus details are not repeated. In someembodiments, the conductive features over the dielectric layer 130 mayalso include conductive pads that will be electrically coupled tounder-bump-metallurgy (UBM) structures formed in subsequent processing,which conductive pads are electrically coupled to one or more of theconductive features 133/135.

Referring next to FIG. 9, a dielectric layer 140 is formed over thedielectric layer 130 and the conductive features 133/135. The dielectriclayer 140 may comprise a same or a similar material as the dielectriclayer 110, and may be formed by a same or similar formation method asthe dielectric layer 110, thus details are not repeated. A planarizationprocess, such as CMP, may be performed to achieve a planar upper surfacefor the dielectric layer 140.

Next, openings (not shown) are formed in the dielectric layer 140 toexpose the conductive pads over the dielectric layer 130, using, e.g.,photolithography and/or etching processes. Once the openings are formed,UBMs 147 may be formed in electrical contact with the conductive pad. Inan embodiment, the UBMs 147 comprises three layers of conductivematerials, such as a layer of titanium, a layer of copper, and a layerof nickel. However, there are many suitable arrangements of materialsand layers, such as an arrangement of chrome/chrome-copperalloy/copper/gold, an arrangement of titanium/titanium tungsten/copper,or an arrangement of copper/nickel/gold, that are suitable for theformation of the UBM 147. Any suitable materials or layers of materialthat may be used for the UBMs 147 are fully intended to be includedwithin the scope of the present disclosures.

The UBMs 147 may be created by forming each layer over the dielectriclayer 140 and along the interior of the openings through the dielectriclayer 140 to the conductive pad. The forming of each layer may beperformed using a plating process, such as electrochemical plating,although other processes of formation, such as sputtering, evaporation,or PECVD process, may alternatively be used depending upon the materialsused. Once the layers of the UBM have been formed, a suitablephotolithographic and/or etching process(es) may be performed to removeportions of the layers and to leave the UBMs 147 in a designed shape,such as a circular, octagonal, square, or rectangular shape, althoughany suitable shape may alternatively be formed.

Still referring to FIG. 9, external connectors 149 are formed on theUBMs 147. In an embodiment, the external connectors 149 are contactbumps such as controlled collapse chip connection (C4) bumps andcomprise a material such as tin, or other suitable materials, such assilver or copper. In an embodiment in which the external connectors 149are tin solder bumps, the external connectors 149 may be formed byinitially forming a layer of tin through any suitable method such asevaporation, electroplating, printing, solder transfer, ball placement,or the like. Once a layer of tin has been formed on the structure, areflow is performed in order to shape the material into the bump shapewith a diameter, e.g., of about 80 μm.

However, while the external connectors 149 have been described above asC4 bumps, these are merely intended to be illustrative and are notintended to limit the embodiments. Rather, any suitable type of externalcontacts, such as microbumps, copper pillars, a copper layer, a nickellayer, a lead free (LF) layer, an electroless nickel electrolesspalladium immersion gold (ENEPIG) layer, a Cu/LF layer, a Sn/Ag layer, aSn/Pb, combinations of these, or the like, may alternatively beutilized. Any suitable external connector, and any suitable process forforming the external connectors, may be utilized for the externalconnectors 149, and all such external connectors are fully intended tobe included within the scope of the embodiments.

As illustrated in FIGS. 3-9, the conductive features, such as conductivelines 113/conductive vias 115 (see FIG. 4), conductive lines123/conductive vias 125 (see FIG. 6), and conductive lines133/conductive vias 135 (see FIG. 8), re-route or redistribute signalsto/from the die 107, thus are referred to as redistribution layers(RDLs). The redistribution layers, together with the associateddielectric layers, such as 110, 120, 130 and 140, are collectivelyreferred to as a redistribution structure.

In the illustrated example of FIG. 9, the ground trenches 117 and theground vias 128 are electrically coupled to one or more externalconnectors 149A via the conductive lines and/or the conductive vias ofthe redistribution structure. The external connectors 149A areelectrically coupled to electrical ground (not shown), thus groundingthe ground trenches 117 and the ground vias 128, in some embodiments.The ground trenches 117 and the ground vias 128 may also be electricallycoupled to one or more die connector 109A, which die connectors 109A areconfigured to be electrically grounded. The ground trenches 117 and theground vias 128, which are electrically coupled to the electrical ground(e.g., having a same voltage as the electrical ground), are used toprovide shielding from electromagnetic interferences (e.g., cross-talk),in some embodiments. In some embodiments, the ground trenches 117 andthe ground vias 128 are electrically coupled to a power supply (e.g.,having a same voltage as a power supply such as a 5V or 3V power supply,not shown) to provide shielding from electromagnetic interferences. Foranalysis of high frequency electromagnetic signals (e.g.,electromagnetic interferences), the electrical ground and the powersupply in a system may be regarded as being electrically shorted, andtherefore, the ground trenches 117 and the ground vias 128, when coupledto the power supply, may also provide shielding from electromagneticinterferences. In other words, to provide shielding from electromagneticinterferences, the ground trenches 117 and the ground vias 128 may bedirectly coupled to the electrical ground, or directly coupled to thepower supply. The discussion of various embodiments herein may use theexample where the ground trenches (e.g., 117) and/or the ground vias(e.g., 128) are electrically coupled (e.g., directly coupled) to theelectrical ground to provide shielding from electromagneticinterferences, with the understanding that the ground trenches (e.g.,117) and/or the ground vias (e.g., 128) may also be electrically coupled(e.g., directly coupled) to the power supply to provide shielding fromelectromagnetic interferences. In other words, in the variousembodiments discussed herein, the electrical ground or the ground plane(e.g., a copper plane directly coupled to the electrical ground) coupledwith the ground trenches 117 and/or the ground vias 128 forelectromagnetic shielding may be replaced with the power supply or thepower plane (e.g., a copper plane directly coupled to the power supply).These and other variations are fully intended to be included within thescope of the present disclosure.

Although the ground trenches 117 and the ground vias 128 are formed inthe same processing steps as the redistribution structure, the groundtrenches 117 and the ground vias 128 are not used for routinginformation bearing signals (e.g., digital waveforms carrying controlsignals and/or data signals) to/from the die 107. Instead, the groundtrenches 117 and the ground vias 128 form an electrically conductivestructure which is electrically grounded, and the electrically groundedconductive structure functions as a shielding structure to reduce oreliminate cross-talk between adjacent signal lines, as will be discussedin more details with reference to FIGS. 10A-10D.

Referring now to FIG. 10A, a carrier de-bonding processing is performedto remove the carrier 101. In some embodiments, the semiconductor device100 in FIG. 9 is flipped over (not shown), and the external connectors149 are attached to a tape (not shown) supported by a frame (not shown).The tape may be a dicing tape, which may be adhesive, for holding thesemiconductor device 100 in place in subsequent processing. Next, thecarrier 101 is detached (de-bonded) from the semiconductor device 100through a de-bonding process. The de-bonding process may remove carrier101 using any suitable process, such as etching, grinding, andmechanical peel off. In some embodiments, carrier 101 is de-bonded byshining a laser or UV light over the surface of carrier 101. The laseror UV light breaks the chemical bonds of the dielectric layer 103 thatbinds to the carrier 101, and carrier 101 can then be easily detached.Although not shown, a dicing processing may be performed after thecarrier de-bonding process to singulate the plurality of semiconductordevices formed over carrier 101 into individual semiconductor devices100.

FIGS. 10B and 10C illustrate cross-sectional views of the semiconductordevice 100 along cross-sections A-A and B-B, respectively. Note thatcross-section B-B is across the ground via 128, whereas cross-sectionA-A is between two adjacent ground vias 128. Referring to FIG. 10B, twoground trenches 117 extend through the dielectric layer 110. Aconductive line 113S is over the upper surface of the dielectric layer110 and between the two ground trenches 117. Although one of the groundtrenches 117 and the conductive line 113S are not visible in thecross-sectional views of FIGS. 1-9 and 10A, one skilled in the art, uponreading FIGS. 10B-10D, will appreciate that the features illustrated inFIGS. 10B-10D, such as the two ground trenches 117 and the conductiveline 113S, are formed in corresponding processing steps of the processflow illustrated in FIGS. 1-9.

Referring to FIG. 10B, the ground trench 117 has an upper portion 117Tover the upper surface of the dielectric layer 110 and a lower portion117B between the upper surface of the dielectric layer 110 and the lowersurface of the dielectric layer 110. Due to various factors such as thedeposition process used to fill the trench opening 112 and/or the sizeof the trench opening 112, an upper surface of a center region of theupper portion 117T may be lower (e.g., closer to the molding material105) than an upper surface of a peripheral region of the upper portion117T, in some embodiments. The lower portion 117T of the ground trench117, which is surrounded by the dielectric layer 110, extends from thelower surface of the dielectric layer 110 facing the molding material105 to the upper surface of the dielectric layer 110 facing away fromthe molding material 105, as illustrated in FIG. 10B. The lower portionof the ground trench 117 may have tapering sidewalls. In other words,the lower portion of the ground trench 117 may have a trapezoidalcross-section, which may due to tapering sidewalls of the trench opening112 caused by the photolithography and etching process used to form thetrench opening 112.

Still referring to FIG. 10B, the conductive line 113S (also referred toas signal line) carries information bearing signals, such as digitalwaveforms that represent control signals or data signals. A controlsignal may comprise a time-varying voltage that switches among aplurality of pre-determined voltage levels, as an example. A data signalmay be a base-band (e.g., un-modulated) signal or a modulated signal(e.g., modulated to a carrier frequency). The data signal may carrierinformation bits that represent voice, text, image, video, or the like,and the information bits may be mapped to data symbols using variousmapping and modulation schemes such as amplitude shift keying (ASK),phase shift keying (PSK), frequency shift keying (FSK), quadratureamplitude modulation (QAM), or the like.

As integration density becomes increasing higher in semiconductormanufacturing, the distance between adjacent signal lines becomescloser. Cross-talk may happen between closely spaced signal lines (e.g.,conductive line 113S) through various coupling mechanisms, such ascapacitive coupling, inductive coupling, or conductive coupling. Due tocross-talk, a first signal transmitted on a first signal line mayinterfere with a second signal transmitted on a second signal line,thereby causing distortion of the second signal and reducing the signalintegrity of the second signal. Conversely, the second signal mayinterfere with the first signal and reduce the signal integrity of thefirst signal. Various embodiments of shielding structures, e.g.,electrically conductive structures which are grounded and which shield asignal line from other nearby signal lines, are disclosed in the presentdisclosure for reducing or eliminating cross-talk, thus improving thesignal integrity and performance of the semiconductor device.

Still referring to FIG. 10B, a height H₁ of the signal line 113S issmaller than a height H₂ of the ground trench 117, wherein H₁ and H₂ aremeasured along a direction perpendicular to the upper surface of themolding material 105. In other words, a ratio of H₂/H₁ is larger than 1.The larger height H₁ helps to shield the signal line 113S from nearby oradjacent signal lines, thus reducing the cross-talk.

In some embodiments, a ratio of D₁/D₂ is larger than or equal to 0.1 andsmaller than or equal to 5 (e.g., 0.1<D₁/D₂<5), where D₂ is the width ofthe signal line 113S, and D₁ is the distance between signal line 113Sand the ground trench 117. In some embodiments, the ratio of D₁/D₂ isdetermined by the characteristics of the electromagnetic (EM) field ofthe signal line (e.g., 113S) to ensure effective shielding provided bythe ground trench (e.g., 117). For example, if the ratio of D₁/D₂ is toosmall (e.g., smaller than 0.1), e.g., due to the ground trench 117 beingtoo close to the signal line 113S, the EM field of the signal line 113Smay be too strong at the location of the ground trench 117, and maycross the ground trench 117 to adversely affect another signal line (notshown) on an opposing side of the ground trench 117 from the signal line113S. On the other hand, if the ratio of D₁/D₂ is too large (e.g.,larger than 5), e.g., due to the ground trench 117 being far away fromthe signal line 113S, the EM field of the signal line 113S at thelocation of the ground trench 117 may be weak, in which case the groundtrench 117 may not be needed. FIG. 10B also illustrates the conductivelines 129 which are disposed on the upper surface of the dielectriclayer 120. The conductive lines 129 are disposed over the groundtrenches 117, and connect the ground vias 128 (see FIG. 10A) together.

FIG. 10C illustrates the cross-sectional view of the semiconductordevice 100 in FIG. 10A, but along cross-section B-B. FIG. 10C is similarto FIG. 10B, but with the ground vias 128 illustrated in thecross-sectional view. In the illustrated example of FIG. 10C, eachground via 128 has an upper portion 128T on the upper surface of thedielectric layer 120. The lower portion of the ground via 128 is in thedielectric layer 120 and is between the upper portion 128T of the groundvia 128 and the upper portion 117T of a corresponding ground trench 117.Therefore, the ground via 128 and the corresponding ground trench 117are electrically connected. In some embodiments, a total height H₃ ofground via 128 and the ground trench 117 is twice or more than (e.g.,twice to five times) the height H₁ of the signal line 113S, where theheight H₃ and the height H₁ are measured along the directionperpendicular to the upper surface of the molding material 105. Forexample, the height H₁ may be between about 0.5 μm and about 10 μm, anddepending on the height H₁, the height H₃ may be between about 2 μm andabout 50 μm. Note that as illustrated in FIG. 10C, the bottom surface ofthe ground trench 117 contacts a dielectric material (e.g., moldingmaterial 105), and the sidewalls of the lower portion 117B of the groundtrench 117 are surrounded by the dielectric layer 110, thus noelectrically conductive feature is connected to (e.g., directlycontacts) the bottom surface of the ground trench 117 or connected tothe lower portion 117B of the ground trench 117. Instead, electricalconnection of the ground trench 117 to another electrically conductivefeature is achieved through the upper portion 117T of the ground trench117, e.g., through the ground vias 128 or through the conductive lines113A/113B (see FIG. 4). In other words, electrical connection of theground trench 117 to another electrically conductive feature is achievedonly through the upper portion 117T of the ground trench 117, in someembodiments.

In the example of FIG. 10C, the ground via 128 on the right ismisaligned with the ground trench 117 on the right, thus a center axis128C of the ground via 128 on the right is not aligned with (e.g., noton a same line with) a center axis 117C of the underlying ground trench117, although 128C and 117C may be parallel to each other and may bothbe perpendicular to the upper surface of the molding material 105. Incontrast, the ground via 128 on the left is vertically aligned with(e.g., directly over) the ground trench 117 on the left, thus the centeraxis of the ground via 128 on the left is aligned with (e.g., on a sameline with) with the center axis of the ground trench 117 on the left. Byallowing for misalignment of the ground vias 128 and the underlyingground trenches 117, the requirements for the accuracy of the patterningprocess (e.g., photolithography process) is reduced, and a larger errormargin is allowed, which allows for lost-cost production and also helpsto improve the yield of the manufacturing process. The misalignment ofthe ground vias 128 and the underlying ground trenches 117 also makes iteasier to pattern the layout of the semiconductor device 100.

FIG. 10C is a non-limiting example. Other configurations are possible.For example, the ground vias 128 on the left and right may each bealigned with a corresponding underlying ground trench 117. As anotherexample, the ground vias 128 on the left and right may each bemisaligned with the corresponding underlying ground trench 117. In theexample of FIG. 10C, a lateral distance (e.g., measured along ahorizontal direction in FIG. 10C) between the ground via 128 on theright and the signal line 113S is larger than a lateral distance betweenthe ground trench 117 on the right and the signal line 113S. In otherwords, the ground via 128 on the right is further from the signal line113S than the underlying ground trench 117. This is an example and notintended to be limiting, and other configurations are possible. Forexample, the ground via 128 may be closer to the signal line 113S thanthe underlying ground trench 117. As another example, one of the groundvias 128 (e.g., on the left or on the right) illustrated in FIG. 10C maybe closer to the signal line 113S than the underlying ground trench 117,while the other one of the ground vias 128 may be further from thesignal line 113S than the underlying ground trench 117. These and othervariations are fully intended to be included within the scope of thepresent disclosure.

FIG. 10D is a cross-sectional of the semiconductor device 100 in FIG.10B along cross-section C-C. As illustrated in FIG. 10D, a longitudinalaxis 117L of the ground trenches 117 is parallel to a longitudinal axis113SL of the signal line 113S. Therefore, the ground trench 117 isparallel to at least the illustrated portion of the signal line 113S.The ground vias 128 are not in the cross-section C-C, thus are shown inphantom in FIG. 10D. In the illustrated embodiment, the centers of theplurality of ground vias 128 on the left are aligned (e.g., overlap)with the longitudinal axis 117L of the underlying ground trench 117. Thecenters of the plurality of ground vias 128 on the right, however, areon a line 128L which is parallel to, but not overlapping with, thelongitudinal axis 117L of the underlying ground trench 117. Note thatthe longitudinal axis 117L of the ground trenches 117 is parallel to theupper surface of the molding material 105, as illustrated in FIG. 10D. Alongitudinal axis of the vias, such as the via 115/125/135 and theground via 128, may be perpendicular to the upper surface of the moldingmaterial 105.

As illustrated in FIG. 10D, a length L₁ of the ground trenches 117,measured along the longitudinal axis 117L of the ground trench 117, isorders of magnitude larger (e.g., 5 times to 100 times, or more) than alength L₂ of the ground via 128 measured along the longitudinal axis117L, which length L₂ may be a same or similar to the length of othervias (e.g., 115/125/135) measured along the direction of 117L. Forexample, for a particular processing node, the length of a via (e.g.,115) may be in a range between about 5 μm and about 100 μm, the lengthL₁ of the ground trench (e.g., 117) may be in a range between about 25μm and about 10000 μm, such as between 200 μm and 5000 μm.

Note that the electrically grounded shielding structure does not have tobe formed along the entirety of the signal lines 113S. Instead, theelectrically grounded shielding structure may be formed along segmentsof the signal lines 113S that are susceptible to cross-talk, e.g., atlocations where the pitch between the signal line 113S and anotheradjacent signal line is 50 μm or less. As another example, theelectrically grounded shielding structure may be formed along segmentsof some signal lines 113S that carry digitally modulated signals withdense constellations (e.g., 64-QAM signals, 126-QAM signals, or 256 QAMsignals), since signals with dense constellations may be less resistantto cross-talk.

Modifications to the embodiment illustrated in FIGS. 1-9 and 10A-10D arepossible and are fully intended to be included within the scope of thepresent disclosure. For example, although four dielectric layers (e.g.,110, 120, 130 and 140) are shown in FIGS. 10A-10D, more or less thanfour dielectric layers may be used in forming the grounded shieldingstructure. As another example, the ground trenches 117 are shown to beformed in the lowest (e.g., closest to the molding material 105)dielectric layer 110 in FIGS. 10A-10D, however, the ground trenches 117may be formed in other (e.g., higher) dielectric layers. In addition,more than one layers of ground trenches may be formed. For example, aground trench 117 may be formed directly over and connected to anotherunderlying ground trench 117, thereby forming a double-layered groundtrench. Furthermore, a ground plane may be formed over and connected tothe ground trenches and/or the ground vias, thereby shielding the signalline 113S from the above, thus forming a grounded shielding structurecomprising a ground plane, ground trenches, and/or ground vias.Additional embodiments illustrating the different configurations for thegrounded shielding structure are discussed below. In the discussionhereinafter, unless otherwise stated, the same numeral in differentfigures refers to the same or similar component that is formed of thesame or similar material(s) by the same or similar method, thus detailsare not repeated.

FIGS. 11A-11C illustrate cross-sectional views of a semiconductor device200, in accordance with some embodiments. FIG. 11B is a cross-sectionalview of the semiconductor device 200 shown in FIG. 11A, but alongcross-section D-D. FIG. 11C is a cross-sectional view of thesemiconductor device 200 shown in FIG. 11B, but along cross-section E-E.Compared with the semiconductor device 100 in FIGS. 10A-10D, thesemiconductor device 200 has less dielectric layers, and does not havethe ground vias 128 and the conductive lines 129 connecting the groundvias 128. Therefore, the electrically grounded shielding structure ofFIGS. 11A-11C simply comprises the ground trenches 117.

As illustrated in FIGS. 11A and 11B, the semiconductor device 200 hastwo dielectric layers 110 and 120 over the molding material 105. Groundtrenches 117 are formed in the dielectric layer 110. Signal line 113S isover the dielectric layer 110 and between the ground trenches 117. FIG.11A illustrates a via 115′ that is formed directly over (e.g.,contacting) the molding material 105 and electrically coupled to theground trench 117. In some embodiments, due to manufacturingconsiderations such as metal density control, the length of the groundtrench 117 (e.g., measured along the direction 117L in FIG. 11C) may besubject to certain constraints and may not be formed to a sufficientlength, in which case the via 115′ may be formed next to the groundtrench 117 and electrically coupled with the ground trench 117. The via115′ may act as an extension of the ground trench 117 to further enhancethe EM shielding capability of the ground trench 117. Vias similar tothe via 115′ are also illustrated in FIGS. 12A, 13A, 14A, 15A, 16A, and17A. Although one via 115′ is illustrated in FIG. 11A, more than onevias 115′ may be formed. These and other variations are fully intendedto be included within the scope of the present disclosure.

The dimensions of the same or similar components in various embodimentsmay have the same or similar relationships. For example, a height H₁ ofthe signal line 113S in FIG. 11B is smaller than a height H₂ of theground trench 117 in FIG. 11B, wherein H₁ and H₂ are measured along adirection perpendicular to the upper surface of the molding material105. In other words, a ratio of H₂/H₁ is larger than 1. In someembodiments, a ratio of D₁/D₂ in FIG. 11B is larger than or equal to 0.1and smaller than or equal to 5 (e.g., 0.1<D₁/D₂<5), where D₂ is thewidth of the signal line 113S, and D₁ is the distance between signalline 113S and the ground trench 117. FIG. 11C illustrates thelongitudinal axis 117L of the ground trench 117, which is parallel tothe longitudinal axis 113SL of the signal line 113S and parallel to theupper surface of the molding material 105.

For simplicity, the dimensions of the same or similar features invarious embodiments, as well as the relationships (e.g., larger,smaller, ratio) between the dimensions of the same or similar featuresin various embodiments may not be repeated for each embodiment, with theunderstanding that the dimensions and the relationships of thedimensions of various features discussed above may apply to the same orsimilar features discussed hereinafter.

FIGS. 12A-12C illustrate cross-sectional views of a semiconductor device300, in accordance with some embodiments. FIG. 12B is a cross-sectionalview of the semiconductor device 300 shown in FIG. 12A, but alongcross-section F-F. FIG. 12C is a cross-sectional view of thesemiconductor device 300 shown in FIG. 12B, but along cross-section G-G.Compared with the semiconductor device 200 in FIGS. 11A-11C, thesemiconductor device 300 has more (e.g., three instead of two)dielectric layers, and the ground trenches 127 are formed in thedielectric layer 120 instead of the lowest (e.g., closest to the moldingmaterial 105) dielectric layer 110. Therefore, the electrically groundedshielding structure of FIGS. 12A-12C comprises the ground trenches 127.

As illustrated in FIG. 12B, the ground trench 127 has a bottom portion127B on the upper surface of the dielectric layer 110, a top portion127T on the upper surface of the dielectric layer 120, and a middleportion 127M in the dielectric layer 120 and connecting the bottomportion 127B with the top portion 127T. The middle portion 127M isnarrower than the top portion 127T and the bottom portion 128B, in theillustrated example of FIG. 12B. A height H₁ of the signal line 113S inFIG. 12B is smaller than a height H₄ of the ground trench 127 in FIG.12B, wherein H₁ and H₄ are measured along the direction perpendicular tothe upper surface of the molding material 105.

FIGS. 13A-13C illustrate cross-sectional views of a semiconductor device400, in accordance with some embodiments. FIG. 13B is a cross-sectionalview of the semiconductor device 400 shown in FIG. 13A, but alongcross-section H-H. FIG. 13C is a cross-sectional view of thesemiconductor device 400 shown in FIG. 13B, but along cross-section I-I.

The electrically grounded shielding structure of semiconductor device400 comprises a lower ground trench 117 in dielectric layer 110 and anupper ground trench 127 in dielectric layer 120. Therefore, theembodiment of FIGS. 13A-13C may be considered as a combination of theembodiment of FIGS. 11A-11C and the embodiment of FIGS. 12A-12C. Inaccordance with some embodiments, a height H₁ of the signal line 113S inFIG. 13B is smaller than a height H₅ of the electrically groundedshielding structure comprising the lower ground trench 117 and the upperground trench 127. In particular, a ratio of H₅/H₁ may be between about2 and about 8.

In FIG. 13B, the center axis of the upper ground trench 127 is alignedwith (e.g., on a same line with) the center axis of the underlying lowerground trench 117. In alternative embodiments, such as illustrated bythe semiconductor device 400′ of FIG. 13D, the center axis 127C of theupper ground trench 127 on the right is not aligned with (e.g., on adifferent line from) the center axis 117C of the lower ground trench 117on the right. In some embodiments, a distance between the lower groundtrenches 117 on the left and on the right is different from a distancebetween the upper ground trench 127 on the left and on the right.Although not illustrated, both the upper ground trenches 127 (e.g., onthe left and on the right) may be misaligned with the respectiveunderlying lower ground trenches 117. These and other variations arefully intended to be included within the scope of the presentdisclosure.

FIGS. 14A-14E illustrate cross-sectional views of a semiconductor device500, in accordance with some embodiments. FIGS. 14B and 14C arecross-sectional views of the semiconductor device 500 shown in FIG. 14A,but along cross-sections J-J and K-K, respectively. FIGS. 14D and 14Eare cross-sectional views of the semiconductor device 500 shown in FIG.14B, but along cross-sections M-M and L-L, respectively.

The semiconductor device 500 is similar to the semiconductor device 100illustrated in FIGS. 10A-10D, but with three dielectric layers insteadof four dielectric layers over the molding material 105. In addition,the semiconductor device 500 has a ground plane 126 formed on the uppersurface of the dielectric layer 120, which ground plane 126 iselectrically connected to the ground vias 128 and the ground trench 117.Therefore, the electrically grounded shielding structure of thesemiconductor device 500 comprises the ground trenches 117, the groundvias 128, and the ground plane 126.

Referring to FIGS. 14B and 14C, the ground trenches 117 extend throughthe dielectric layer 110, and have upper portions 117T on the uppersurface of the dielectric layer 110. The ground vias 128 are formed inthe dielectric layer 120 over the ground trenches 117. The ground plane126 are formed on the upper surface of the dielectric layer 120, andextends continuously over the signal line 113S and the ground vias 128disposed on opposing sides of the signal line 113S. The ground plane iselectrically and mechanically coupled to the ground vias 128.

As illustrated in FIG. 14C, the ground vias 128 on the left are alignedwith (e.g., disposed directly over) the underlying ground trench 117.The ground vias 128 on the right are not aligned with the underlyingground trench 117. For example, the center axis 128C of the ground vias128 on the right is misaligned (e.g., not on a same line) with thecenter axis 117C of the underlying ground trench 117.

As illustrated in FIG. 14D, the centers of the plurality of ground vias128 on the left are aligned (e.g., overlap) with the longitudinal axis117L of the underlying ground trench 117. The centers of the pluralityof ground vias 128 on the right, however, are on a line 128L which isparallel to, but not overlapping with, the longitudinal axis 117L of theunderlying ground trench 117.

FIG. 14E illustrates the ground plane 126, which extends continuouslyfrom the ground vias 128 (shown in phantom) on the left to the groundvias 128 on the right. Also illustrated in FIG. 14E is the signal line113S (shown in phantom), which is between the ground vias 128 on theleft and the ground vias on the right. The ground plane 126 iselectrically connected to the ground vias 128 and the ground trenches117, thus shielding the signal line 113S from the top to further reducecross-talk.

Variations are possible and are fully intended to be included within thescope of the present disclosure. In some embodiments, the ground vias128 on the left and on the right are aligned with respective underlyingground trenches 117. In some embodiments, the ground vias 128 on theleft and on the right are misaligned with respective underlying groundtrenches 117. As another example, the lateral distance between thesignal line 113S and the ground via 128 (e.g., the ground via 128 on theleft or on the right) may be larger than or smaller than the lateraldistance between the signal line 113S and the ground trench 117underlying the ground via 128.

FIGS. 15A-15D illustrate cross-sectional views of a semiconductor device600, in accordance with some embodiments. FIG. 15B is a cross-sectionalview of the semiconductor device 600 shown in FIG. 15A, but alongcross-section N-N. FIGS. 15C and 15D are cross-sectional views of thesemiconductor device 600 shown in FIG. 15B, but along cross-section O-Oand P-P, respectively.

The semiconductor device 600 is similar to the semiconductor device 500illustrated in FIGS. 14A-14E, but with the ground vias 128 replaced withupper ground trenches 127. To distinguish the ground trenches 117(formed in the dielectric layer 110) from the upper ground trenches 127(formed in the dielectric layer 120), the ground trenches 117 arereferred to as the lower ground trenches in the discussion of thesemiconductor device 600. Therefore, the electrically grounded shieldingstructure of the semiconductor device 600 comprises the lower groundtrenches 117, the upper ground trenches 127, and the ground plane 126.

FIG. 15C shows the lower ground trenches extending parallel to thesignal line 113S. FIG. 15D shows the ground plane 126 extendingcontinuously over the upper ground trenches 127 (shown in phantom) andthe signal line 113S (shown in phantom).

In FIG. 15B, the upper ground trenches 127 are shown to be verticallyaligned (e.g., directly over) with the underlying lower ground trenches117. This is merely a non-limiting example. In another embodiment, asemiconductor device 600′ illustrated in FIG. 15E has similar structuresas the semiconductor device 600, but with the upper ground trench 127 onthe right misaligned with the underlying lower ground trench 117. Forexample, the center axis 127C of the upper ground trench 127 on theright is not on a same line as the center axis 117C of the underlyingground trench 117. In yet another embodiment, as illustrated in FIG.15F, a semiconductor device 600″ has similar structures as thesemiconductor device 600, but with the upper ground trenches 127 on theleft and on the right misaligned with the respective underlying groundtrenches 117. In particular, the center axis 127C of the upper groundtrench 127 on the right is further from the signal line 113 than thecenter axis 117C of the underlying ground trench 117, and the centeraxis 127C of the upper ground trench 127 on the left is closer to thesignal line 113 than the center axis 117C of the underlying groundtrench 117. Various modifications are possible and are fully intended tobe included within the scope of the present disclosure.

FIGS. 16A-16D illustrate cross-sectional views of a semiconductor device700, in accordance with some embodiments. FIG. 16B is a cross-sectionalview of the semiconductor device 700 shown in FIG. 16A, but alongcross-section Q-Q. FIGS. 16C and 16D are cross-sectional views of thesemiconductor device 700 shown in FIG. 16B, but along cross-section S-Sand R-R, respectively.

The semiconductor device 700 is similar to the semiconductor device 600illustrated in FIGS. 15A-15D, but with the lower ground trenches 117removed. Therefore, the electrically grounded shielding structure of thesemiconductor device 700 comprises the upper ground trenches 127 and theground plane 126.

As illustrated in FIG. 16B, the upper ground trenches 127 has a bottomportion 127B on the upper surface of the dielectric layer 120 and amiddle portion 127M in the dielectric layer 120 and over the bottomportion 127B. Portions of the upper ground trenches 127 over thedielectric layer 120 merge with the ground plane 126, and may beconsidered as part of the ground plane 126, thus are not labeled. In theillustrated example of FIG. 16B, the bottom portion 127B has a widthlarger than a width of the middle portion 127M.

FIGS. 17A-17D illustrate cross-sectional views of a semiconductor device800, in accordance with some embodiments. FIG. 17B is a cross-sectionalview of the semiconductor device 800 shown in FIG. 17A, but alongcross-section T-T. FIGS. 17C and 17D are cross-sectional views of thesemiconductor device 800 shown in FIG. 17B, but along cross-section U-U.

Referring to FIG. 17A, an electrically conductive feature 117′ is formedin the dielectric layer 110 using similar material and formation methodas the ground trench 117 in other embodiments, such as in FIGS. 11A-11C.However, unlike the ground trench 117 which is electrically grounded andused as (part of) a shielding structure to reduce cross-talk, theelectrically conductive feature 117′ is electrically connected to a linevia 104 and used to reduce DC resistance, which in turn reduces the IRdrop of the semiconductor device 800.

As illustrated in FIGS. 17A-17C, the line via 104 comprises electricallyconductive paths (see 104 in FIG. 17C) formed in the dielectric material108 of the die 107, which dielectric material 108 surrounds the dieconnectors 109. While the die connectors 109 route signals (e.g.,electrical current) in a direction perpendicular to the upper surface ofthe die 107 and has cross-sections (e.g., in a top view) such ascircles, ovals, squares, or rectangles, the line vias 104 route signalsin a plane substantially parallel to the upper surface of the die 107and has cross-sections (e.g., in the top view) comprising segments ofconductive lines. For example, FIG. 17C shows the line vias 104 asconductive lines connecting a plurality of contact pads P1 (may also bereferred to power contact pads) of the die 107, which contact pads P1are electrically coupled to a power supply of the die 107 denoted aspower domain 1. FIG. 17C also illustrates a plurality of contact pads P2of the die 107, which are electrically coupled to another power supplyof the die 107 denoted as power domain 2. FIG. 17C further illustrates aplurality of contact pads GND of the die 107, which are electricallycoupled to the electrical ground. The die 107 may have other contactpads, such as contact pads for routing control and data signals, whichare not shown in FIG. 17C.

FIG. 17D is similar to FIG. 17C, but with the electrically conductivefeatures 117′, which are not visible in the cross-sectional view of FIG.17C, shown in phantom to illustrate the locations of the electricallyconductive features 117′ relative to the line vias 104. As illustratedin FIG. 17D, the electrically conductive features 117′ are formeddirectly over the line vias 104, and therefore, overlap the line vias104, in some embodiments. The electrically conductive features 117′ maycompletely overlap the line vias 104 and thus, comprises continuousconductive paths connecting power contact pads P1, in some embodiments.In other embodiments, the electrically conductive features 117′ may beformed over segments of the line vias 104, and therefore, comprisesdiscrete segments 118 that are separated from each other. A longitudinalaxis of the electrically conductive features 117′ is parallel to thefront side of the die 107, or parallel to the upper surface of themolding material 105, in some embodiments.

The electrically conductive features 117′ effectively increase thethickness and/or the volume of the line vias 104, thus reducing the DCresistance of the power contact pads P1, which in turn reduces the IRdrop of the die 107. In advanced semiconductor process node, the powersupply voltage drops from higher voltage, e.g., 5 V to lower voltagesuch as 1.2 V. Since the power consumption of the chip may remain thesame or even increase due to more functionality being integrated intothe chip, the current of the chip increases. The increased chip currentposes more stringent requirements for the IR drop of the chip, since thesame DC resistance in a higher voltage (e.g., 5V) design may result inunacceptable IR drop in the lower voltage (e.g., 1.2V) design. Theembodiment of FIGS. 17A-17D reduces the DC resistance of the powercontact pads P1, thus making it easier for the chip design in advancedprocess node to meet the stringent IR drop requirements.

FIG. 18 illustrates a flow chart of a method of forming a semiconductordevice, in accordance with some embodiments. It should be understoodthat the embodiment method shown in FIG. 18 is merely an example of manypossible embodiment methods. One of ordinary skill in the art wouldrecognize many variations, alternatives, and modifications. For example,various steps as illustrated in FIG. 18 may be added, removed, replaced,rearranged and repeated.

Referring to FIG. 18, at step 1010, a die is embedded in a moldingmaterial. At step 1020, a first dielectric layer is formed over themolding material and the die. At step 1030, a conductive line is formedover an upper surface of the first dielectric layer facing away from thedie. At step 1040, a second dielectric layer is formed over the firstdielectric layer and the conductive line. At step 1050, a first trenchis formed extending through a first one of the first dielectric layerand the second dielectric layer, where a longitudinal axis of the firsttrench is parallel with a longitudinal axis of the conductive line. Atstep 1060, the first trench is filled with an electrically conductivematerial to form a first ground trench.

Embodiments may achieve advantages. The electrically grounded shieldingstructure may be formed in the same processing steps as forming theredistribution structures. Due to the simple structures of the disclosedembodiments, low production cost is achieved. Simulation results haveshown that the disclosed embodiments effectively reduces cross-talk. Forexample, compared with a design without the presently disclosedfeatures, the presently disclosed embodiments provide about 5 dB or morereduction in cross-talk from 1 GHz to about 10 GHz. In addition, thedisclosed embodiment in FIGS. 17A-17D provides a low-cost design thatcan reduce the DC resistance and IR drop of the die 107, which mayimprove the performance of the die 107 and help to meet the stringent IRdrop requirements for chip design in advanced process nodes.

In an embodiment, a semiconductor device includes a die; a moldingmaterial around the die; a first dielectric layer over the die and themolding material, the first dielectric layer having a first surfacefacing the die and a second surface opposing the first surface; aconductive line along the second surface of the first dielectric layer;and a second dielectric layer over the first dielectric layer and theconductive line, the second dielectric layer having a third surfacefacing the die and a fourth surface opposing the third surface. Thesemiconductor device further includes a first conductive structurelaterally spaced from and parallel with at least a first portion of theconductive line, where the first conductive structure is configured tobe electrically grounded or connected to a power supply; and a secondconductive structure laterally spaced from and parallel with at leastthe first portion of the conductive line, where the first portion of theconductive line is between the first conductive structure and the secondconductive structure, where a first portion of the first conductivestructure and a first portion of the second conductive structure arebetween the first surface and the second surface or between the thirdsurface and the fourth surface, and where a longitudinal axis of thefirst portion of the first conductive structure and a longitudinal axisof the first portion of the second conductive structure are parallel tothe first surface of the first dielectric layer. In an embodiment, theconductive line has a first height, where the first conductive structureand the second conductive structure have a second height larger than thefirst height, where the first height and the second height are measuredalong a direction perpendicular to an upper surface of the moldingmaterial. In an embodiment, the first conductive structure and thesecond conductive structure extend through the first dielectric layerand the second dielectric layer. In an embodiment, each of the firstconductive structure and the second conductive structure includes alower ground trench in the first dielectric layer and an upper groundtrench in the second dielectric layer, the lower ground trench connectedto the upper ground trench. In an embodiment, a distance between thelower ground trench of the first conductive structure and the lowerground trench of the second conductive structure is different from adistance between the upper ground trench of the first conductivestructure and the upper ground trench of the second conductivestructure. In an embodiment, the first conductive structure includes afirst ground trench that extends through the first dielectric layer, andthe second conductive structure includes a second ground trench thatextends through the first dielectric layer. In an embodiment, the firstconductive structure further includes first plurality of ground vias inthe second dielectric layer and connected to the first ground trench,and the second conductive structure further includes second plurality ofground vias in the second dielectric layer and connected to the secondground trench. In an embodiment, the semiconductor device furtherincludes a ground plane over the fourth surface of the second dielectriclayer, where the ground plane extends over the conductive line, thefirst conductive structure and the second conductive structure, andwhere the ground plane is connected to the first plurality of groundvias and the second plurality of ground vias. In an embodiment, thefirst conductive structure includes a first ground trench that extendsthrough the second dielectric layer, and the second conductive structureincludes a second ground trench that extends through the seconddielectric layer. In an embodiment, the semiconductor device furtherincludes a ground plane over the fourth surface of the second dielectriclayer, where the ground plane extends over the conductive line, thefirst ground trench and the second ground trench, and where the groundplane is connected to the first ground trench and the second groundtrench.

In an embodiment, a method includes embedding a die in a moldingmaterial; forming a first dielectric layer over the molding material andthe die; forming a conductive line over an upper surface of the firstdielectric layer facing away from the die; forming a second dielectriclayer over the first dielectric layer and the conductive line; forming afirst trench opening extending through the first dielectric layer or thesecond dielectric layer, where a longitudinal axis of the first trenchis parallel with a longitudinal axis of the conductive line, and whereno electrically conductive feature is exposed at a bottom of the firsttrench opening; and filling the first trench opening with anelectrically conductive material to form a first ground trench. In anembodiment, a bottom of the first ground trench contacts the moldingmaterial. In an embodiment, a first height of the first ground trench islarger than a second height of the conductive line, where the firstheight and second height are measured along a direction perpendicular tothe upper surface of the first dielectric layer. In an embodiment, thefirst trench opening extends through the first dielectric layer, wherethe method further includes forming a second trench opening extendingthrough the second dielectric layer, where a longitudinal axis of thesecond trench opening is parallel with the longitudinal axis of theconductive line; and filling the second trench opening with theelectrically conductive material to form a second ground trench, thesecond ground trench electrically and mechanically coupled to the firstground trench. In an embodiment, a first lateral distance between theconductive line and the first ground trench is different from a secondlateral distance between the conductive line and the second groundtrench. In an embodiment, the first trench opening extends through thefirst dielectric layer, where the method further includes forming aplurality of ground vias in the second dielectric layer, where theplurality of ground vias is aligned on a line that is parallel to thelongitudinal axis of the conductive line, and where the plurality ofground vias is electrically and mechanically coupled to the first groundtrench. In an embodiment, the method further includes forming a groundplane over an upper surface of the second dielectric layer, where theground plane extends over the conductive line and the plurality ofground vias, and where the ground plane is electrically and mechanicallycoupled to the plurality of ground vias.

In an embodiment, a device includes a die that includes a conductivepillar and a line via that are in a same dielectric layer on a frontside of the die, where the conductive pillar and the line via areelectrically coupled to respective contact pads of the die, and wherethe line via comprises a conductive path extending parallel to the frontside of the die; a molding material around the die; a first dielectriclayer over the molding material and the die; a first conductive lineover the first dielectric layer; and an electrically conductivestructure extending through the first dielectric layer and connected tothe line via and the first conductive line, where a longitudinal axis ofthe electrically conductive structure is parallel to the front side ofthe die. In an embodiment, the line via is electrically coupled to acontact pad of the die that is configured to be coupled to a powersupply voltage. In an embodiment, the device further includes a secondconductive line over the first dielectric layer; and a via in the firstdielectric layer, where the via is connected to the second conductiveline and the conductive pillar.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A semiconductor device comprising: a die embedded in a molding material; a first dielectric layer over the die and the molding material; a conductive line along an upper surface of the first dielectric layer distal to the die; a second dielectric layer over the first dielectric layer and the conductive line; and a first conductive structure and a second conductive feature on opposing sides of the conductive line and spaced apart from the conductive line, wherein the first conductive feature and the second conductive feature extend through at least the first dielectric layer or the second dielectric layer, wherein a first longitudinal axis of the first conductive feature and a second longitudinal axis of the second conductive feature are parallel to a third longitudinal axis of the conductive line.
 2. The semiconductor device of claim 1, wherein the conductive line has a first height measured along a first direction perpendicular to an upper surface of the molding material, wherein the first conductive structure and the second conductive structure have a second height measured along the first direction, where a ratio between the second height and the first height is larger than
 1. 3. The semiconductor device of claim 1, wherein a width of the conductive line is D2, and a distance between the conductive line and the first conductive structure is D1, wherein a ratio between D1 and D2 is between about 0.1 and about
 5. 4. The semiconductor device of claim 1, wherein the first conductive structure comprises a first ground trench that extends through the first dielectric layer, and the second conductive structure comprises a second ground trench that extends through the first dielectric layer.
 5. The semiconductor device of claim 4, wherein the first conductive structure further comprises a first plurality of ground vias in the second dielectric layer and connected to the first ground trench, and the second conductive structure further comprises a second plurality of ground vias in the second dielectric layer and connected to the second ground trench.
 6. The semiconductor device of claim 5, further comprising a ground plane over the second dielectric layer and connected to the first plurality of ground vias and to the second plurality of ground vias, wherein the ground plane extends continuously from the first plurality of ground vias to the second plurality of ground vias.
 7. The semiconductor device of claim 5, wherein the first plurality of ground vias are disposed along a first line parallel to the third longitudinal axis of the conductive line, and the second plurality of ground vias are disposed along a second line parallel to the first line.
 8. The semiconductor device of claim 7, wherein in a top view, a first distance between the first line and the third longitudinal axis is smaller than a second distance between the second line and the third longitudinal axis.
 9. The semiconductor device of claim 1, wherein the first conductive structure and the second conductive structure extend through the first dielectric layer and the second dielectric layer.
 10. The semiconductor device of claim 9, wherein each of the first conductive structure and the second conductive structure comprises a lower ground trench in the first dielectric layer and an upper ground trench in the second dielectric layer, the lower ground trench connected to the upper ground trench.
 11. The semiconductor device of claim 10, wherein a first distance between the lower ground trench of the first conductive structure and the lower ground trench of the second conductive structure is different from a second distance between the upper ground trench of the first conductive structure and the upper ground trench of the second conductive structure.
 12. The semiconductor device of claim 10, further comprising a ground plane over the second dielectric layer and connected to the upper ground trench of the first conductive structure and the upper ground trench of the second conductive structure, wherein the ground plane extends continuously from the upper ground trench of the first conductive structure to the upper ground trench of the second conductive structure.
 13. A semiconductor device comprising: a die surrounded by a molding material; a first dielectric layer over the molding material; a conductive line along a first surface of the first dielectric layer facing away from the die; a second dielectric layer over the conductive line and the first dielectric layer; and an electromagnetic (EM) shielding structure at least partially in the first dielectric layer or the second dielectric layer, the EM shielding structure comprising: a first conductive feature on a first side of the conductive line; and a second conductive feature on a second opposing side of the conductive line, wherein longitudinal axes of the first conductive feature and the second conductive feature are parallel to a first longitudinal axis of the first conductive line.
 14. The semiconductor device of claim 13, wherein a first bottom surface of the first conductive feature and a second bottom surface of the second conductive feature are in physical contact with the molding material, wherein the first bottom surface and the second bottom surface face the molding material.
 15. The semiconductor device of claim 13, wherein the first conductive feature comprises a first ground trench in the first dielectric layer, and the second conductive feature comprises a second ground trench in the first dielectric layer.
 16. The semiconductor device of claim 15, further comprising a ground plane over the second dielectric layer, the ground plane extending over the first ground trench, the conductive line, and the second ground trench, the ground plane electrically coupled to the first ground trench and the second ground trench.
 17. A method comprising: embedding a die in a molding material; forming a first dielectric layer over the molding material and the die; forming a conductive line over an upper surface of the first dielectric layer facing away from the die; forming a first trench opening extending through the first dielectric layer, wherein a longitudinal axis of the first trench opening is parallel with the upper surface of first dielectric layer, and the molding material is exposed at a bottom of the first trench opening; and filling the first trench opening with an electrically conductive material to form a first ground trench.
 18. The method of claim 17, wherein the first ground trench is formed to have a first height larger than a second height of the conductive line, wherein the first height and the second height are measured along a direction perpendicular to the upper surface of the first dielectric layer.
 19. The method of claim 17, further comprising: forming a second dielectric layer over the first dielectric layer; and forming a plurality of ground vias in the second dielectric layer, wherein the plurality of ground vias is disposed along on a line parallel to a longitudinal axis of the conductive line, wherein the plurality of ground vias is electrically and mechanically coupled to the first ground trench.
 20. The method of claim 17, further comprising: forming a second dielectric layer over the first dielectric layer; forming a second trench opening extending through the second dielectric layer, wherein a longitudinal axis of the second trench opening is parallel with a longitudinal axis of the conductive line, the second trench opening exposing the first ground trench; and filling the second trench opening with the electrically conductive material to form a second ground trench. 